Rights groups are calling for an investigation into a Sri Lankan air force bombing of what the government says was a training center for the Tamil Tiger separatist group and the rebels say was a children's center. The incident has reignited debate about the children who are unwillingly forced to take part in Sri Lanka's bitter conflict.

Early reports of the bombing in the eastern district of Mullaitivhu on August 14 appeared on the pro-rebel Web page, Tamilnet. The Web site said four Sri Lankan air force jets dropped 16 bombs on a children's center, where students, most of them girls, were taking a first-aid course.

Tamilnet ran four photos, one apparently showing the bodies of 12 girls. The Web page said 61 people were killed and dozens were injured.

The U.N. children's organization UNICEF says at least 19 people died in the bombing. The agency believes all those killed were aged between 16 and 18.

UNICEF and human rights groups say they want the government to investigate the attack.

Sri Lankan officials confirm the air force bombed the compound. But National Security spokesman Keheliya Rambukwella says if those killed were children, it is only because they were illegally conscripted by the Tamil Tiger rebels, also called the LTTE.

"The fact is that gender or the age limit is of no concern, when it come to training them, when it comes to soldiers, because they are carrying arms in order to kill the enemy. This time the enemy is government forces. So even if it [is] a 17 year-old child in terms of age, they are soldiers who are prepared to kill," he said. "What is important is that the LTTE has taken these people [and] trained them."

The Sri Lankan military has released video footage from a spy plane that shows people in dark uniforms fleeing the bombed area, suggesting, officials say, that adult Tamil Tiger soldiers were present.

The incident has again focused attention on the use of child soldiers in Sri Lanka.

The government and the Tamil Tigers signed a ceasefire agreement in 2002, raising hopes of an end not only to two decades of civil war, but also to the conscription of child soldiers.

Throughout the conflict, rights groups say, the rebels have forced children into their ranks as part of their campaign for an independent homeland for the country's ethnic Tamil minority.

But hopes the practice would end were soon dashed. In a report released in November 2004, the U.S. organization Human Rights Watch says the Tamil Tigers conscripted more than 35-hundred child soldiers in the two and a half years after the ceasefire was signed.

The use of child soldiers is one of the reasons the United States designates the group a terrorist organization.

Now the ceasefire has all but collapsed, with clashes breaking out between the rebels and government forces in eastern and northern Sri Lanka. Rights groups say that puts children at renewed risk - such as in the recent bombing incident.

Under international law, it is illegal to take military action against children. If the children
are soldiers, all other possible means should be used to try to counter them as a potential threat.

International law also demands that armed groups such as the Tamil Tigers ensure that they do not endanger children by their actions, or bring children near camps or military installations that could be legitimate war targets.

James Ross, a senior legal adviser with Human Rights Watch, says that given available evidence, the government cannot justify the Mullaitivhu bombing.

"The bottom line here is that even if the Tamil Tigers were giving some kind of training to benefit their own forces, no evidence has been presented that would show that these particular students or young people were actively participating in the hostilities, which would be the standard for when a civilian could actually be targeted," commented Ross. "So, the Sri Lankan government, it's not just a matter that training is going on, they'd actually have to show that these were forces actively participating in hostilities."

Rifts within the rebel movement are compounding the problem of child conscription.

In 2004, the Tamil Tigers split into two factions. The commander of the breakaway faction goes by the alias Karuna.

The Tamil Tigers charge that the Sri Lankan government orchestrated that split, and the Karuna group is a paramilitary organization working for the government - charges that officials deny. The group does have an office in the Sri Lanka capital, which has police protection.

UNICEF says the Karuna group is conscripting children, with 30 cases verified in one week in June alone.

"What we have seen is recruitment by a new faction, the Karuna faction, with fairly significant numbers recruited between the months of April and June," said JoAnna VanGerpen, the UNICEF representative in Sri Lanka. "It was off in July but now we're hearing new reports again of recruitment. This is a very unfortunate development."

Ross from Human Rights Watch says it is very worrying that the government apparently is complicit in the Karuna group's conscripting of children.

"The fact that abductions appear to be taking place in Batticaloa area by the Karuna Group, and the camps in which these children who are abducted have been taken are in areas of government control, that is government involvement in this activity," said Ross. "And that's what we're concerned about."

A Sri Lankan government spokesman says that it welcomes the Karuna group's effort to become part of the political mainstream, but that does not mean the government approves of all of its actions.

After months of brinksmanship, Sri Lanka's government and the Tamil Tigers are facing the prospect of renewed civil war. The nation's children, it appears, will be caught in the crossfire.